Conventionally, there has been studied a stereoscopic display device configured to project, in the air, a stereoscopic image that an observer can visually recognize without using an instrument dedicated for observing the stereoscopic image such as polarized glasses (for example, refer to Patent Documents 1 to 3).
For example, the stereoscopic display device disclosed in Patent Document 1 has a synthetic stereoscopic image formed electronically, an imaging unit to reproduce a real image of the synthetic stereoscopic image, and a focusing device to almost match a focal position of eyes of an observer with a position of the real image. Further, this stereoscopic display device has a z-direction scanning unit, a rotary scanning unit, and a matrix type display as a formation unit of the synthetic stereoscopic image in order to increase display performance.
Moreover, a stereoscopic two-dimensional image display device disclosed in Patent Document 2 has an image transmission panel, an imaging portion display object, and a housing. The image transmission panel is disposed parallel to, and apart from an image display surface, and is made up of a microlens array made up of a plurality of lenses and having a valid area wider than that of an image to be displayed, and a lens frame region surrounding a periphery of the valid region of the microlens array. The image transmission panel generates an imaging surface configured to display a real image of a two-dimensional image in a space on an opposite side of a display unit of the microlens array and located in front of the lens frame region. The imaging portion display object is disposed in the vicinity of the imaging surface, and the housing encloses an optical path between the display unit and the image transmission panel to make the optical path dark.
Further, an optical imaging device disclosed in Patent Document 3 uses first and second light control panels formed by arranging a great number of band-shaped flat light reflectors side by side at a constant pitch in a surface on one side of a transparent flat plate inside the transparent flat plate. One-surface sides of the respective first light control panel and second light control panel are disposed in opposition to one another so that the flat light reflectors are perpendicular to one another.